diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 32bf66a..25ce4ac 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -37,6 +37,7 @@
         "libsurfaceflinger_unittest_main.cpp",
         "AllowedDisplayConfigsTest.cpp",
         "CompositionTest.cpp",
+        "DispSyncSourceTest.cpp",
         "DisplayIdentificationTest.cpp",
         "DisplayTransactionTest.cpp",
         "EventControlThreadTest.cpp",
diff --git a/services/surfaceflinger/tests/unittests/DispSyncSourceTest.cpp b/services/surfaceflinger/tests/unittests/DispSyncSourceTest.cpp
new file mode 100644
index 0000000..92bdebd
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/DispSyncSourceTest.cpp
@@ -0,0 +1,164 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#undef LOG_TAG
+#define LOG_TAG "LibSurfaceFlingerUnittests"
+#define LOG_NDEBUG 0
+
+#include <inttypes.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <log/log.h>
+
+#include "AsyncCallRecorder.h"
+#include "Scheduler/DispSyncSource.h"
+#include "mock/MockDispSync.h"
+
+namespace android {
+namespace {
+
+using namespace std::chrono_literals;
+using testing::Return;
+
+class DispSyncSourceTest : public testing::Test, private VSyncSource::Callback {
+protected:
+    DispSyncSourceTest();
+    ~DispSyncSourceTest() override;
+
+    void createDispSync();
+    void createDispSyncSource();
+
+    void onVSyncEvent(nsecs_t when) override;
+
+    std::unique_ptr<mock::DispSync> mDispSync;
+    std::unique_ptr<DispSyncSource> mDispSyncSource;
+
+    AsyncCallRecorder<void (*)(nsecs_t)> mVSyncEventCallRecorder;
+
+    static constexpr std::chrono::nanoseconds mPhaseOffset = 6ms;
+    static constexpr int mIterations = 100;
+};
+
+DispSyncSourceTest::DispSyncSourceTest() {
+    const ::testing::TestInfo* const test_info =
+            ::testing::UnitTest::GetInstance()->current_test_info();
+    ALOGD("**** Setting up for %s.%s\n", test_info->test_case_name(), test_info->name());
+}
+
+DispSyncSourceTest::~DispSyncSourceTest() {
+    const ::testing::TestInfo* const test_info =
+            ::testing::UnitTest::GetInstance()->current_test_info();
+    ALOGD("**** Tearing down after %s.%s\n", test_info->test_case_name(), test_info->name());
+}
+
+void DispSyncSourceTest::onVSyncEvent(nsecs_t when) {
+    ALOGD("onVSyncEvent: %" PRId64, when);
+
+    mVSyncEventCallRecorder.recordCall(when);
+}
+
+void DispSyncSourceTest::createDispSync() {
+    mDispSync = std::make_unique<mock::DispSync>();
+}
+
+void DispSyncSourceTest::createDispSyncSource() {
+    createDispSync();
+    mDispSyncSource = std::make_unique<DispSyncSource>(mDispSync.get(), mPhaseOffset.count(), true,
+                                                       "DispSyncSourceTest");
+    mDispSyncSource->setCallback(this);
+}
+
+/* ------------------------------------------------------------------------
+ * Test cases
+ */
+
+TEST_F(DispSyncSourceTest, createDispSync) {
+    createDispSync();
+    EXPECT_TRUE(mDispSync);
+}
+
+TEST_F(DispSyncSourceTest, createDispSyncSource) {
+    createDispSyncSource();
+    EXPECT_TRUE(mDispSyncSource);
+}
+
+TEST_F(DispSyncSourceTest, noCallbackAfterInit) {
+    createDispSyncSource();
+    EXPECT_TRUE(mDispSyncSource);
+
+    // DispSyncSource starts with Vsync disabled
+    mDispSync->triggerCallback();
+    EXPECT_FALSE(mVSyncEventCallRecorder.waitForUnexpectedCall().has_value());
+}
+
+TEST_F(DispSyncSourceTest, waitForCallbacks) {
+    createDispSyncSource();
+    EXPECT_TRUE(mDispSyncSource);
+
+    mDispSyncSource->setVSyncEnabled(true);
+    EXPECT_EQ(mDispSync->getCallbackPhase(), mPhaseOffset.count());
+
+    for (int i = 0; i < mIterations; i++) {
+        mDispSync->triggerCallback();
+        EXPECT_TRUE(mVSyncEventCallRecorder.waitForCall().has_value());
+    }
+}
+
+TEST_F(DispSyncSourceTest, waitForCallbacksWithPhaseChange) {
+    createDispSyncSource();
+    EXPECT_TRUE(mDispSyncSource);
+
+    mDispSyncSource->setVSyncEnabled(true);
+    EXPECT_EQ(mDispSync->getCallbackPhase(), mPhaseOffset.count());
+
+    for (int i = 0; i < mIterations; i++) {
+        mDispSync->triggerCallback();
+        EXPECT_TRUE(mVSyncEventCallRecorder.waitForCall().has_value());
+    }
+
+    EXPECT_CALL(*mDispSync, getPeriod()).Times(1).WillOnce(Return(16666666));
+    mDispSyncSource->setPhaseOffset((mPhaseOffset / 2).count());
+
+    EXPECT_EQ(mDispSync->getCallbackPhase(), (mPhaseOffset / 2).count());
+
+    for (int i = 0; i < mIterations; i++) {
+        mDispSync->triggerCallback();
+        EXPECT_TRUE(mVSyncEventCallRecorder.waitForCall().has_value());
+    }
+}
+
+TEST_F(DispSyncSourceTest, pauseCallbacks) {
+    createDispSyncSource();
+    EXPECT_TRUE(mDispSyncSource);
+
+    mDispSyncSource->setVSyncEnabled(true);
+    EXPECT_EQ(mDispSync->getCallbackPhase(), mPhaseOffset.count());
+    mDispSync->triggerCallback();
+    EXPECT_TRUE(mVSyncEventCallRecorder.waitForCall().has_value());
+
+    mDispSyncSource->pauseVsyncCallback(true);
+    mDispSync->triggerCallback();
+    EXPECT_FALSE(mVSyncEventCallRecorder.waitForUnexpectedCall().has_value());
+
+    mDispSyncSource->pauseVsyncCallback(false);
+    mDispSync->triggerCallback();
+    EXPECT_TRUE(mVSyncEventCallRecorder.waitForUnexpectedCall().has_value());
+}
+
+} // namespace
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp b/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp
index 2f7e5ea..f6c4f62 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp
+++ b/services/surfaceflinger/tests/unittests/mock/MockDispSync.cpp
@@ -15,6 +15,7 @@
  */
 
 #include "mock/MockDispSync.h"
+#include <thread>
 
 namespace android {
 namespace mock {
@@ -23,5 +24,39 @@
 DispSync::DispSync() = default;
 DispSync::~DispSync() = default;
 
+status_t DispSync::addEventListener(const char* /*name*/, nsecs_t phase, Callback* callback,
+                                    nsecs_t /*lastCallbackTime*/) {
+    if (mCallback.callback != nullptr) {
+        return BAD_VALUE;
+    }
+
+    mCallback = {callback, phase};
+    return NO_ERROR;
+}
+status_t DispSync::removeEventListener(Callback* callback, nsecs_t* /*outLastCallback*/) {
+    if (mCallback.callback != callback) {
+        return BAD_VALUE;
+    }
+
+    mCallback = {nullptr, 0};
+    return NO_ERROR;
+}
+
+status_t DispSync::changePhaseOffset(Callback* callback, nsecs_t phase) {
+    if (mCallback.callback != callback) {
+        return BAD_VALUE;
+    }
+
+    mCallback.phase = phase;
+    return NO_ERROR;
+}
+
+void DispSync::triggerCallback() {
+    if (mCallback.callback == nullptr) return;
+
+    mCallback.callback->onDispSyncEvent(
+            std::chrono::steady_clock::now().time_since_epoch().count());
+}
+
 } // namespace mock
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDispSync.h b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
index 901cf15..afcda5b 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
@@ -36,14 +36,27 @@
     MOCK_METHOD1(setPeriod, void(nsecs_t));
     MOCK_METHOD0(getPeriod, nsecs_t());
     MOCK_METHOD1(setRefreshSkipCount, void(int));
-    MOCK_METHOD4(addEventListener, status_t(const char*, nsecs_t, Callback*, nsecs_t));
-    MOCK_METHOD2(removeEventListener, status_t(Callback*, nsecs_t*));
-    MOCK_METHOD2(changePhaseOffset, status_t(Callback*, nsecs_t));
     MOCK_CONST_METHOD1(computeNextRefresh, nsecs_t(int));
     MOCK_METHOD1(setIgnorePresentFences, void(bool));
     MOCK_METHOD0(expectedPresentTime, nsecs_t());
 
     MOCK_CONST_METHOD1(dump, void(std::string&));
+
+    status_t addEventListener(const char* name, nsecs_t phase, Callback* callback,
+                              nsecs_t lastCallbackTime) override;
+    status_t removeEventListener(Callback* callback, nsecs_t* outLastCallback) override;
+    status_t changePhaseOffset(Callback* callback, nsecs_t phase) override;
+
+    nsecs_t getCallbackPhase() { return mCallback.phase; }
+
+    void triggerCallback();
+
+private:
+    struct CallbackType {
+        Callback* callback = nullptr;
+        nsecs_t phase;
+    };
+    CallbackType mCallback;
 };
 
 } // namespace mock